The Oxford Thesaurus An A-Z Dictionary of Synonyms - carelessadj.

1) unconcerned, untroubled, unworried, casual, indifferent, heedless, thoughtless, inconsiderate, uncaring, devil-may-care, irresponsible, cursory, lackadaisical, perfunctory: No one could approve of the careless way he treats his family. 2) inattentive, negligent, thoughtless, absent-minded, neglectful, remiss; unobservant, unthinking, imprudent, unmindful, incautious, unwary, reckless, slapdash, rash: Many of the errors come from being careless. 3) inaccurate, imprecise, inexact, incorrect, wrong, error-ridden, erroneous, Colloq sloppy: You won't get a good mark for such a careless paper. 4) unstudied, ingenuous, artless, casual, nonchalant: I dislike his careless way of dressing, but it does show some style.